How to preserve the flavor of summer tomatoes? I love the whole concept of canning, but more often than not I’ll opt for low-heat and a deep freeze instead. After roasting, let the tomatoes cool to room temperature and pop the whole pan in the freezer (this freezes them individually, so they’re easy to separate later). When the tomatoes are firm (usually after just an hour), slide them into a Ziploc bag and keep them in the freezer for luscious, flavorful roasted tomatoes all winter long.